The present invention is a process for the preparation of hydrolyzable beta-cyanoalkylsilanes. More particularly, this invention relates to the catalytic addition of silicon hydrides to .alpha., .beta.-unsaturated olefinic nitriles to form .beta.-cyanoalkylsilanes. The present invention employs tetraalkylammonium halide supported on silica gel as a catalyst.
Hydrolyzable beta-cyanoalkylsilanes are useful for the production of polyorganosiloxanes containing the beta-cyanoalkyl substituent. The silicon-bonded beta-cyanoalkyl radical is extremely resistant to hydrolysis and cleavage under hot, humid conditions. Therefore, beta-cyanoalkylsilanes find particular use in the preparation of polyorganosiloxanes which must be subjected to hot, humid conditions. The presence of the silicon-bonded beta-cyanoalkyl radical substituted on polyorganosiloxanes also tends to stabilize the polyorganosiloxanes against swelling induced by liquid hydrocarbons.
Jex et al., U.S. Pat. No. 2,906,764, issued Sep. 29, 1959, describe a process for producing cyanoalkylsilanes by reacting an olefinic nitrile with a silane, the silane having at least one hydrogen and one hydrolyzable group bonded to the silicon atom, in the presence of a diarylamine catalyst.
Pike et al., J. Org. Chem. 24, 1939-42, 1959, describe tertiary amines as effective directive catalysts for the reaction of trichlorosilane with acrylonitrile to form beta-cyanoethyltrichlorosilane.
Pike et al., J. Org. Chem. 27, 2190-92, 1962, describe preparation of beta-cyanoethyltrichlorosilane by reacting trichlorosilane with acrylonitrile in the presence of silylamine catalysts of the general formula (CH.sub.3).sub.3 SiNR.sub.2, where the nitrogen atom of the silylamine is attached to the silicon atom.
Bluestein, U.S. Pat. No. 2,971,970, issued Feb. 14, 1961, describes a process for reacting hydrolyzable silicon hydride with an .alpha.,.beta.-unsaturated olefinic nitrile to form a cyanoalkylsilane where the catalyst comprises (A) a cuprous compound, (B) a diamine, and (C) a trialkylamine.
Bluestein, U.S. Pat. No. 2,971,972, issued Feb. 14, 1961, describes a process for reacting phenyldichlorosilane and acrylonitrile to form .beta.-cyanoethylphenyldichlorosilane without the necessity for employing a diamine. The process is conducted in the presence of a cuprous compound selected from a group consisting of cuprous oxide and cuprous halides, and in the presence of a trialkylamine.
Rajkumar et al., Organometallics 8, 549-550, 1989, describe a catalyst system consisting of tetramethylethylenediamine and cuprous oxide for the hydrosilylation of acrylonitrile to give the .beta.-adduct.
Bank, U.S. Pat. No. 5,126,468, issued Jun. 30, 1992, describes a process for the preparation of hydrolyzable .beta.-cyanoalkylsilanes by the catalytic addition of hydrolyzable silicon hydrides to .alpha., .beta.-unsaturated olefinic nitriles. The process employs a catalyst comprising a diamine and nonactivated copper or a compound of copper selected from a group consisting of copper metal, Cu(II) halide, Cu(II) oxide, copper sulfate, copper sulfide, and copper cyanide compounds, Cu(I) thiocyanide, and copper chromium compounds.
Bank, U.S. Pat. No. 5,126,469, issued Jun. 30, 1992, describes a process for the preparation of hydrolyzable .beta.-cyanoalkylsilanes by the catalytic addition of hydrolyzable silicon hydrides to .alpha., .beta.-unsaturated olefinic nitriles using a supported catalyst. The supported catalyst comprises a diamine and supported copper or a support copper compound.